In recent years, with the development of information technology, an image processing technique related to augmented reality (AR), in which visual information is added to an image acquired by capturing an image of a reality space (a real world) using a computer, has been under development. In displaying visual information, mainly, a wearable device, such as a head mounted display (HMD) to which a camera that captures an image in the real world is attached, and the like, a tablet terminal provided with a camera, and the like, are used, and detailed information (which will be hereinafter referred to as an additional information image (or may be referred to as a virtual world image)) related to a recognition target object that exists in the visual filed direction of a user is superimposed on an object in the real world and thus displayed.
Currently, a technology for supporting identification of a failure part at the occurrence of a failure of an electronic device or the like, and failure repairing work by a user using an augmented reality technology has been realized. For example, a technique in which, in support for repairing work for repairing a failure of sheet jamming, an internal video image of a copy machine and an image of operation procedures, which are additional information images and have been prepared in advance in association with a sheet jamming occurrence position, are superimposed and thus displayed in the copy machine, which is a recognition target object, has been proposed. For example, in “Proposal and Evaluation of a Supporting Method for NPP Decommissioning Work by Augmented Reality”, Transaction of the Virtual Reality Society of Japan, 2008, pp. 289-300, vol. 13 No. 2, work support using augmented reality has been proposed also in a field work of maintenance and inspection, equipment installation and dismantlement, or the like, in an industrial plant.
In user work support, since, in many cases, a user works using the both hands, there are great demands for utilization of a HMD, which is head-wearable and hands-free, rather than a tablet terminal. HMDs are largely divided into two types, that is a video see-through type HMD, which displays an additional information image, in addition to a captured image of a camera, on a display unit, such as a display and the like, and an optical see-through type HMD, which displays an additional information image in association with the position of an object in the real world visually recognized by a user using a half mirror on a display unit. Considering a visual filed limit due to a field angle of a camera and the occurrence of a time lag from image capturing to image displaying, there might be cases where use of the video see-through type HMD in a field work is not appropriate. On the other hand, in the optical see-through type HMD, a user actually visually observes a recognition target object in the real world, and therefore, the optical see-through type HMD has an advantage in which there is not a visual limit due to the field angle and a time lag. For this reason, there have been demands for work support by augmented reality using the optical see-through type HMD.